WordArt text effects and transforms, and shape connectors (#416)

[vangel76]

What

WordArt

• Run-level text effects ([MS-DOCX] w14:textFill, w14:textOutline, w14:shadow, w14:glow, w14:reflection): solid / linear-gradient / no fill, outline colour and width, shadow, glow, fading reflection. Model (wordcraft_doc::wordart), DOCX read/write, drawn from glyph outlines as paint layers in the rasteriser and the PDF (invisible glyphs keep the PDF text extractable).
• Transform warps (a:prstTxWarp + a:avLst adjust values in wps:bodyPr): all 41 presets round-trip; arch up/down, circle, wave, slant up/down, inflate/deflate, chevron up/down and triangle up/down are drawn bent (glyph outlines flattened and mapped through the preset geometry); others draw flat. Unknown presets are dropped, adjust values capped.
• insert.wordArt now makes a floating, fill-less text box in one of our own styles (theme colours, generic names), optionally bent; format.textEffects (Home › Text Effects), wordArt.style, wordArt.textFill, wordArt.textOutline, wordArt.transform (Shape Format › WordArt Styles). With a shape selected or the caret in a text box, effects apply to the whole box's text.
• UI: style gallery (Insert › WordArt, Home › Text Effects, Shape Format › WordArt Styles), Text Fill / Text Outline / Text Effects (Shadow, Glow, Reflection, Transform) menus; Transform previews are drawn from the warp geometry itself; new icons drawn in code.

Connectors

• Straight, elbow and curved connectors (straightConnector1, bentConnector2–5, curvedConnector2–5 read; 3-segment forms written), arrowheads (a:headEnd/a:tailEnd), glued ends (wps:cNvCnPr a:stCxn/a:endCxn → shape drawing id + site). Glued-to shapes keep their docPr/cNvPr ids; other shapes' ids are dropped on read so existing round trips are unchanged.
• Connection sites: rectangle-like shapes 4 side midpoints, ellipse 8, triangle 6.
• shape.connect glues an end to a shape (by position, nearest site or given site) or drags it to a page point (snaps to a site within 12 pt, else stays free). After object edits (arrange.*, shape.*, picture.*, insert.shape), glued floating connectors in the body re-route from the layout (and connectors inside groups in the group's space), in the same undo step.
• Insert › Shapes lists the connectors; dragging a selected connector's end handle onto a shape glues it (sites shown while dragging).

Clean room: ECMA-376 / [MS-DOCX] only; styles, colours and icons are our own.

How tested

• docx roundtrip: every char prop incl. full text effects; warp + glued connectors + arrowheads + unglued id dropped; hostile XML (unknown warp, huge site index, glue to a missing id).
• layout: arch baselines lie on one ellipse over the top; flat/unknown warps; hostile adjust values stay in the frame.
• doc: hostile effect values capped; group connectors follow their shapes, missing ids/sites ignored.
• engine: nudging/resizing a glued shape re-routes the connector (one undo); dragging an end snaps/frees/refuses bad sites; WordArt insert → Draw::Art, PDF export, capped/invalid params. hostile_params_never_panic green.
• cargo clippy -D warnings on touched crates, cargo xtask layers, cargo xtask wasm, cargo xtask parity (402/434 → 407/439), UI tests (i18n coverage in all 9 catalogs).
• Looked at it headlessly with ui_shot: bent/glowing/gradient/reflected WordArt over body text, elbow and curved connectors following a moved ellipse, the Transform previews and the style gallery.

Fixes #416

Not done

• WordArt 3-D (w14:scene3d/w14:props3d), bevel; text effects on PDF are vector layers (blurs approximated by bands, as for shapes).
• Warped text is edited/selected in its unbent layout (highlights don't follow the warp); the text is stretched over the box like WordArt, the box isn't auto-fitted to the text afterwards.
• Elbow connectors always route out-across-in horizontally (no vertical exits, no avoiding shapes); bentConnector2/4/5 and curvedConnector2/4/5 adjust values aren't kept.
• Connectors re-route on the same page only, for floating body connectors; text edits that reflow paragraph-anchored shapes don't re-route until the next object edit. Copying a glued shape duplicates its id (the first copy wins).
• Shape effects (shadow/glow) aren't drawn on connectors.

🤖 Generated with Claude Code

[echelon]

Thanks for the contribution, @vangel76! This is now merged into main. If you haven't already, please come join us on Discord: https://discord.gg/artcraft